Dyads and Triads Based on Phenothiazine, Bis(terpyridine)ruthenium(II) Complexes, and Fullerene

Abstract

Abstract:We report the modular synthesis of donor-photosensitizer-bridge-acceptor (D-P-B-A) triads and D-P dyads for the formation of photoinduced charge-separated species. The structures are based on a phenothiazine unit (D), a bis(terpyridine) [bis(tpy)] ruthenium(II) complex (P), several phenylene(ethynylene)-type spacer units (B), and a pyrrolidino[60]fullerene entity (A). The donor-acceptor distance is between 18 and 37 Å and was varied by four different bridging units. The photophysical and electrochemical characterization revealed

Superexchange in the fast lane – intramolecular electron transfer in a molecular triad occurs by conformationally gated superexchange

“…For the first electron transfer (PTZ-3 P * -C 60 →PTZ from the neutral, optimized molecular structures. 2,3 For ET1, due to the same electron donor, electron acceptor and the same donor-acceptor distance, identical reorganization energy will be produced which was already shown in a previous study. 12 The calculated reorganization energy for ET2 as a function of temperature is summarized in Table S2-4.…”

“…The synthesis, steady-state emission spectra, electrochemical properties and photoinduced dynamics of 1-3 at room temperature have been reported elsewhere. [1][2][3] Time-Resolved Spectroscopy. Femtosecond (fs) transient absorption (TA) spectra were collected by using a previously reported home-built pump-probe laser system which is based on an amplified Ti:…”

“…8,9 2. Both n and ε s are temperature dependent, ε s (T) = a + bT + cT 2 + dT 3 , for dichloromethane, a = 0.40452×10 2 , b = -0.17748×10 0 , c = 0.23942×10 -3 , d = 0; 10 for dichloromethane n(T) = 1.59078 -5.66×10 -4 T. 11 3. For the first electron transfer (PTZ-3 P * -C 60 →PTZ from the neutral, optimized molecular structures.…”

“…For the first electron transfer step, the radical pairs are tpy •-/ PTZ •+ ; E 00 is the energy difference between the thermalized, lowest 3 MLCT excited state and ground state of Ru complex. E 00 is taken to be 2.07 eV.…”

Energy versus Electron Transfer: Controlling the Excitation Transfer in Molecular Triads

“…electron transfer and energy transfer) in am olecular triad which is comprised of ap henothiazined onor, aR u-terpyridine( tpy) photocenter and af ullerene (energy and electron) acceptor.T he chemical structures of the investigated triad, PTRuC 60 ,a nd ad yad, PTRu,w hich servesa sr eference system, are showni nS cheme 1. [8] The ratio to which the individualt ransfer channels are effective upon photoexcitation can be controlled by changing the excitation wavelength, that is, by preferentiale xcitationo fe ither of the MLCT states associated with the two structurally( and hence electronically) distinctt py ligands coordinating the Ru ion. [9] We show that these distinct MLCT states have different propensities to promote electrono re nergy transfer,w hich would affect the performance of ap otentiald evice in dependence on the excitation conditions.…”